My good friend Mo found this extensive doc (see link) about bolting and anchors. This is the closest I have yet seen to a comprehensive bolting manual. I am impressed with the comprehensiveness and scientific approach of the author.

My request:
i. Peer review. For those in the know, do you agree with the statements in the doc?
ii. Request for more docs - do you know of similar documentation of official nature that can be looked at when researching bolting practices?

I'm trying to take the guesswork out of bolting while trying to avoid the word-of mouth approach.
The doc in the link has a scientific approach, which I like. It gives me a tool to use for selection of method and materials, based on the location (rock type & quality).

To answer your question, I think I am looking for both.

As per my original request: I am hoping some of our tech gurus can read the doc in the link and give an opinion on the content.

1] Use proven existing technology - ie 10x90mm Fischer FBN or Hilti HSA-R anchors with commercially available hangers. (These are good quality stainless steel anchors)
2] Place bolts in solid rock
3] Place bolts to alow for easy clipping, no ankle breaking and to reduce rope drag. Top rope the route and chalk dot the best bolt positions.

I'm not dissing word of mouth, there is a lot of value in learning from the experience of others (and in so doing not repeating mistakes). As an engineer I am however very interested in the science behind what makes an anchor stick, etc.

Invest in quality lower offs
Invest in a torque wrench
Chase quality
Respect existing routes (will your wonder line compromise an existing route)
Ignore those f***ers who backseat drive your efforts and have never tried to open a route

Not trying to hijack the thread, but this sort of discussion is EXACTLY the reason why what both Derek and Frans have done is good.
And others.
Put a bit of science into things.

It's a good thing to publish the test data as well as the results of testing.
As well as the interpretations.
That way it can be used buy other people in THEIR work.

As far as the effect of longer bolts is concerned, then sure, all else being equal they obviously tend to be stronger, but perhaps not greatly so.
As you increase the bolt length, the axial strength increases, but then starts to level out.
In soft rock you'd do probably better by using a different "glue": on that permeates the rock.
Or perhaps a different type of bolt.

The way I'd look at it is that SHORT bolts could be good in very hard rock (to reduce drilling effort), and STANDARD length bolts used in general.
In SOFT rock you should probably look at other measures, I doubt that a small increase from 68mm to 90mm would be enough.